Time controlled register for automatic telephone systems



w; H. MATTHIES' 2,428,376

TIME CONTROLLEIS REGISTER FOB AUTOMATIQ TELEPHONE SYSTEMS Oct. 7, 1947.

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TIME CONTROLLED REGISTER FOR AUTOMATIC TELEPHONE SYSTEMS Filed June 12, 1943 15 Sheets-Sheet 7 T0 TROUBLE ALARM CCT Ir0 TRAFFIC nae. ccr

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A T TORNEV Oct. 7, 17. w. H. MAT THIES 2,428,376 1 TIME CONTROLLED\REGISTER FOR AUTOMATIC TELEPHONE SYSTEMS Filed Jxine 12, 1943 15 Sheets-Sheet 8 TO LAST TRUNK TO INTERM D/ATE SENDEI? a Q Q 6 {u t F N INVENTOR WH; MATTH/ES' 5 a. M'

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ATTORNE V Oct. 7, 1947. w. H. MATTHIES 2,428,376

TIME CONTROLLED REGISTER FOR AUTOMATIC TELEPHONE SYSTEMS Filed June 12, 1943 15 Sheets-Sheet 10 p o; Q

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TIME CONTROLLED REGISTER FOR AUTOMATIC TELEPHONE SYSTEMS Filed June 12, 1943 15 Sheets-Sheet 11 INVENTOR' By Wh. MA 7 7/1/55 ATTORNEY Oct. 7, 1947. w, H, MATTHlEs I 2,428,376

TIME CONTROLLED REGISTER FOR AUTOMATIC TELEPHONE SYSTEMS Filed June 12, 1943 15 Sheeis-Sheet l2 //v l/EN TOR W/v'. MA T TH/ES ATTORNEY Get. 7, 1947. w, MATTHlEs I I 2,428,376

TIME CONTROLLED REGISTER FOR AUTOMATIC TELEPHONE SYSTEMS Filed June 12, 1943 15 Sheets-Sheet l5 INVENTOR w H MATTHIES ATTORNEY Oct. 7, 1947. w. H. MATTHIES 2,428,375

THOUSANDS GROUP TIME CONTROLLED REGISTER FOR AUTOMATIC TELEPHONE SYSTEMS Filed June 12 1945 15 Sheets-Sheet 14 FIG. /4

g. o it w v; I v 3 o E lNVENTOR By rm MATTH/ES A T TORNEV Oct, 7, 1947.. w. H. MATTH-IES 2,428,376

TIME CONTROLLED REGISTER FOR AUTOMATIC TELEPHONE SYSTEMS Filed June 12, 1945 15 Sheets-Sheet 15 a T0 INTERMEOMTE /D[ N T/FIE I? IN 5 N TOR WH MA 77/1/55 By 1 1 i ATTORNEY Patented Oct. 7, 1947 ,tfzisit UNITED STATES PATENT OFFICE TIME CONTROLLED REGISTERFOR AUTO- MATIC TELEPHONE SYSTEMS William H. Matthies, Hackensaok, N. J .,;as sign o;r

'to Bell Telephone Laboratories, Incorporated,

New YorlgN. Y., a corporation of New York Application June 12, 1943,-Serial No. 490,568

(01. ire-#71) 8 Claims.

This invention relates to dial switching telephone systems and -more particularly to telephone systems in which a charge is automatically made for each completed call.

'ln-la rge exchange areas having several ofiices, some of which maybe-located at quite distant points in the area, it'is desirable that means be provided whereby a calling subscriber may be charged differently for calls to ofiices which are most remotely located-from the ofilce in which the calling line terminates than for calls to offices 'which'are not so remotely located since V the remotely located ofiices must be reached over long intero'ffice trunks which are expensive to install and maintain and his not equitable to the operating company to provide service to all points in the exchange area at the same basic rate. Furthermore it is not equitable to the operating company that for a basic charge, the subscriber shallbe enable'dto hold established con nections indefinitely. Both automatic charging in accordance with the zone of the exchange area into which a connection is extended and in accordance with the elapsed conversational period have been heretofore accomplished and whereby the charges io'rove'rtim'e periods 'of conversation may be made in accordance with thezone into which the connection has been extended and on a different basis-than the charges for the initial period of conversation.

It has hereinbeforebeen 'difiicult to apply'this method of charging-to exchange systems employ= ing dial switching apparatus ofthe step bystep type since-in such systems it is customary to connect the message registerof each message rate subscribers 'lineyin parallel with the line cut-off relay and to operate such. message register to charge for an established connectionlby the application of 1a higher. or booster potential to the sleeve conductorof. the calling line to operate the message register following the response of the called subscriber. .It thus*becomeszveryxdifficult to. operate thev message register more than once forany call and-therefore in omces of this type the 'repeatednoperation of a, message i register in .accordancewiththe zone into which the established connection;hasvbeen-extended and in accordance with the number of unit periods of conversation, becomes a very difficult problem to solve.

-With this problem mind, it is theobject of the present. invention to providea solution therefor which will ,enable zone and overtime 'call charging tot-be appliedeto; existing ofiice areas of the step-by-steptype withwa? minimum alteration r in theexisting vcentralofi'ice line and switching the toll ticket as one of the items from which equipment. ;It isof course tobe understood that the invention is equally applicable to other types of systems. 7

It hasheretofore been proposed to equip ofiice areas of the step-by-step type with equipment whereby subscribersmay establish short haul or so-called AB toll calls by dialing, thereby eliminatingthe services of the toll operator on such calls. To accomplishthis it has been proposed to provide facilities for automatically printing on atollticket all of the information which may be required for ticketing or billing such calls to callin g subscribers, that is, the calling and called subscribers-line identifications, the time and date that the call was made, the elapsed time of the conversation and such other data as may be required. A system oi-this type is disclosedin the application ofvJ. W. Gooderham, SerialNo. 448,782, filed June 27, 1942.

In this system in response tothe dialing oi one or moreof the office code digits or letters of a wanted line number, a toll ticketing trunk is seized whereupon an idle sender common to a plurality or ticketing trunks is associated with the trunk over a trunk finder. The seized sender then proceeds to associate itself over a senderidentifier.-connector with an idle calling line identifier and the seized identifier then proceeds to associate itself directly with the seized trunk over an identifier-trunk-connector after which it proceeds toidentifythe calling line and to register the digits identifying the office and number of the calling line. The identifier with the assistance .called office and to the wanted line therein.

With the called ofiiceroute relay operatedythe identifier is also enabled to determine the rate to-be charged for the initial period of conversation. Each ticketing-trunk of this system is also provided with register switches which are advanced periodically following the response of the called subscriber and until the termination of the conversation to register the elapsed time of the conversation which elapsed time is printed on the elapsed time of conversation. In accordance with the present invention, this automatic ticketing equipment has been so modified that it not only is available for performing its automatic ticketing functions on short haul toll calls, but

is also available for handling calls from subscribers lines having message registers and for charging for calls on a zone and overtime basis. On any zone call requiring the operation of calling line message registers, a trunk is seized and if the trunk has access to several offices in a plurality of zones, it causes the association of an idle sender therewith over a trunk finder whereupon a calling line identifier becomes connected with the sender and the trunk in the manner previously described. The identifier then proceeds to reconstruct the office code digits of the wanted line dialed by the calling subscriber and to operate a zone relay in the trunk corresponding to the zone called as determined from the called ofiice code. The identifier is then dismissed without identifying the number of the calling line.

The message registers of the entire calling ofiice are grouped to be selected by a register connector. The trunk is provided with a timing circuit which is started upon the response of the called subscriber and continues in operation until the conversation is terminated and during the initial and each overtime period of conversation causes the identifier to become associated with the trunk and to identify the calling line. In response to each identification of the calling line, the identifier controls the register connector to select the register of the calling line whereby the identifier operates such register in accordance with the zone, initial and overtime registrations in the trunk.

The invention having been described in a general manner, reference may now be had tothe following detailed description thereof taken in connection with the accompanying drawing in which:

Fig. 1 shows schematically in the upper portion thereof, a line finder and selector switches over which lines of a calling office may establish connections to a charging trunk shown in Figs. 4 and 5; in the central portion thereof one of the ten thousands transformer coils and the associated hundreds transformer coils of the thousands number circuit serving the oifice in which the calling line terminates and common to a plurality of calling line identifiers; and in the lower portion thereof a group of hundreds connector relays having access to the corresponding hundreds groups of lines of one of the thousands groups;

Fig. 2 shows in the left portion thereof two of the ten groups of thousands connector relays of the thousands number circuit and in the right portion thereof two of the tens transformer coils for identifying the tens groups and tens digits of the calling line and the units identifying pads of one of the identifiers;

Fig. 3 shows switching relays of an identifier for successively rendering different portions of thecircuits of Figs. 1 and 2 effective and also 4 shows a box indicating the common number and class circuit;

Figs. 4 and 5, taken together, show a complete zone and overtime charging trunk including a digit register, zoneregister relays and an elapsed time measuring switch;

Fig. 6 shows one of the identifier-trunk-connectors for connecting an identifier seized by a sender with the trunk of a group of one hundred trunks which has been connected to the sender;

Fig. 7 shows a trunk finder individual to the sender of which portions are disclosed in the right portion of Fig. 11;

Fig. 8 shows a sender-trunk-connector for connecting any seized sender with the trunk which has seized the sender.

Figs. 9, 10, 12 and 13, the portion of Fig. 11 to the left of the dot-dash line, Fig. 3 and the rightportion of Fig. 2 previously referred to, show in schematic form such portions of the apparatus of an identifier as are necessary to an understanding of the invention; Fig. 9 showing in the right portion thereof switching relays and in the left portion thereof amplifier and detector circuits connectable to the several portions of the identifier circuits through the operation of the SWlBChing relays of .Fig, 2 for detecting the presence of signaling current on the connected sleeve conductor of any calling line and register relays associable with the detector circuit; Fig. 10 showing in the left portion thereof, the register circuit for registering the hundreds digit of the calling line number and in the right portion thereof register circuits for registering the thousands digit of the calling line; Fig. 12 showing register circuits for registering the tens digit of the calling line number; and Fig. 13 showing register circuits for registering the units digits of the calling line number; 7

Fig. 11 shows in the left portion thereof certain control relays of the identifier, in the central portion thereof a sender-identifier-connector for associating a sender seized by a trunk with an idle calling line identifier, in the right portion thereof such elements of a sender as are necessary to an understanding of the invention and in the lower portion thereof message register control relays of the identifier;

Figs. 14 and 15 show the message register connector circuit, Fig. 14 showing two groups of hundreds connector relays having access to corresponding hundreds groups of message registers allocated to the corresponding hundreds groups of lines; and Fig. 15 showing two of the tens groups of thousands connector relays; and

Fig. 1A is a chart showing how the several figures of the drawings should be arranged to disclose the complete invention.

The line finder l0! schematically illustrated in Fig. 1 is of the well-known step-by-step type having two brush sets one of which has access to an upper bank of terminals in which one hundred lines terminate and the otherof which has access to a lower bank of terminals in which a second one hundred lines terminate. Each group of two hundred lines is accessible from a subgroup of line finders, an idle one of which is started upon the initiation of a call from any line of thegroup. The selector switches I92, I03 and H14 schematically disclosed in Fig. 1 are also of the wellknown step-by-step type being directively oper-' able in response to dial im ulses to establish connections to charge trunks over which connections may be further extended to subscribers lines terimin'ating in other offices of the near-by area or saws 5; to-establish connections totoll ticketing trunks over which connections may be further extended to subscribers lines terminating in offices of the near-by toll area. The trunk finder I of Fig. '7 is of the double brush step-by-step type.

The thousands number circuit disclosed in part in Figs. 1- and 2 and the common number circuit indicated by the box 300- in Fig. 3 are identical with the similar circuits disclosedin full-in the G'ooderham application hereinbefore referred to. The sender, only a few relays of which are disclosed in the right portion of Fig. ll is substantially identical with that disclosed in full in the Gooderham application except that two relays H36 and- HM have been added together with associat'ed circuit connections for enabling the sender to function properly on calls requiring zone and overtime message register control. The digit register 400 of the charging trunk of Figs. 4 and 5- is of the rotary step-by-step type which is advanced step-by-step' in response to the dialing of an impulse series by the stepping magnet cm and is restored to normal. by the operation of the release magnet 402. The off-normal contact set 500' of Fig. 5 is operated in response to the movement of the brush. shaft of the register 400 one step cit-normal. The elapsed time switch 550 of Fig. 5 is of the type whose brushes are advanced step-by-step in response to the energization and deenergization of the stepping magnet 55! and advanced to normal in a restoring movement under the control of the stepping magnet.

The sender-identifier-connector I I50 of the Fig. 1-1- is identical with that disclosed in full in the Gooderham application except that provision is made for the extension of two additional control conductors from the identifier to the sender for use in connection with the added relays I I and Hill of the sender. The sender-trunk-connector of Fig. 8 is one of a plurality effective to associate a seized sender with a calling trunk on calls requiring the printing of a toll ticket. One of these circuits would be provided for each subgroup of ten trunks and one of these circuits is taken for use as determined by the operation of the trunk finder I00 in associating a sender with the calling trunk. These connector circuits are identical with the corresponding circuits ofthe Gooderham application. The identifier-trunk-connector of Fig. 6 is one of a plurality effective to associate a seized. identifierwith a calling trunk. One of these circuits would be provided for each subgroup of twenty trunks and one of these circuits is taken for use as determined by the operation of the trunk finder I00 in associating a sender with the calling trunk. These circuits are substantially identical with the corresponding circuits of the G'ooderhamapplication except that additional circuit paths are provided thereover for enabling the identifier to transmit zone registration information to and from the trunk with which the identifier is associated.

To enable a clearer understanding of the invention and the mode of its operation, the manner in which a call from the calling line I00 of Fig. 1 toa called line in another zone of the exchange area will now be described. It will be assumed that the subscriber whose substation is indicated at I00 desiresto secure a connection with a subscribers line whose directory number is assumed to be MAR-I345. When the subscriber removes his receiver from the switchhook, an idle line finder, for example line finder I0'I' is started in the well-known manner to hunt for the callin line and to connect it with the first selector switch 6.. I021 paired with such line finder, whereupon the calling subscriber receives the usual dial tone to indicate that he may then proceed to dial the digits of the directory number of the wanted line.

' It will be assumed that in response to the dialing of the first ofiice code letter M, the second oflice code letter A' and the third office code letter R, the first, second and third selector switches I02, I03 and I04 are operated and a connection is thereby established over the conductors I05, I05, and I01 of an idle trunk I08 to the trunk apparatus disclosed in Figs. 4- and 5.

Upon the seizure of the trunk a circuit is established from ground at the third selector switch I00 over sleeve conductor I01 through the lower winding of sleeve relay 408 of the trunk, over the upper normal contacts of test jack 409, through the winding of relay 4 I0 to battery and in parallel with the winding of relay M0 over the armature and back contact thereof and through resistance Ml to battery. Relay 008 operates from the low resistance battery thus supplied; prepares a locking circuit over its upper winding and uppermost front contacts; short-circuits its lower winding and prepares a circuit over its lower front con tact for a purpose to be later described. Relay H0 also operates and removes resistance MI from the parallel connection with its winding.

As soon as the talking circuit is cut through over the brushes of the selector switches, a circuit is established from ground through the upper Winding of line relay M2 over the lower No. 2 back contact of relay 4 I3, the upper No. 2 normal contacts of relay 4M, tip conductor I05 of the trunk, tipbrushes of the selector switches I00, I03 and I02 and line finder I 0I over the calling line 100p through the substation H20, thence returning over the ring brushes of the line finder MI and selector switches I02, I03 and Hid, ring trunk conductor I06, the lower No. 2 normal contacts of relay M4, the upper No. 2 back contact of relay M3 through the lower winding of relay M2 to battery. Relay M2 thereupon operates closing over its front contact a circuit-for slowto-release relay tliIIi which may be traced from ground over the lower No. 1 back contact of relay M3, over the front contact of relay M2, through the winding of relay M5 to battery and ground. Relay 015 thereupon operates; establishes an obvious circuit for slow-to-release relay H6; prepares over its upper No. 1 contacts a circuit for the stepping magnet MI of the digit register 00 and for the slow-tO-release relay til; connects ground from the lower No. 3 back contact of relay M8 over its upper No. 3 front contact and the upper No. 2 back contact of relay 0 I9 to the trunk finder start conductor 020 which is common to ten trunks of the subgroup; establishes a connection from ground and battery through the winding of relay 4L9 over. the upper No. 3 back contact of relay M8 andthe No. 1 lowerfront contact of relay M5 to conductor IZI to mark the trunk as calling so that the started trunk finder will stop on the terminals of such trunk and over its lower front contact prepares a circuit for the transfer relay M3. Relay H6, upon operating, completes the locking circuit of sleeve relay 408 which may now be traced from battery through the upper winding and over the upper contacts of relay 408, over the upper normal contacts of'jack 409, over the lower No. 2' back contact of relay 422 to ground on the lower front contact of relay M8 to hold relay 468 operated and overthe sleeve conductor I01 of the trunk to-hold the selector switches M2,.

I03 and I00 and-the line finder I-0I from'releasing.

When relay 4| 2 releases due to the opening of the dialing circuit for the first impulse of the thousands numerical digit 1 of the wanted line number, the circuit for magnet MI and the circuit for relay 4II previously prepared by the operation of relay M5 are completed from ground over the lower No. 1 back contact of relay 3, over the back contact of relay M2, the upper No. 1 front contact of relay M2, conductor 423, the lower normal contacts of off-normal contact set 500 of the digit register 400, thelower normal contacts of relay 4 I I to battery through the winding of relay 4H and in parallel therewith to battery through the winding of stepping magnet 40 I. Magnet AM and relay AII both operate. Relay All because of its slow-to-release characteristic remains operated until the termination of the impulse series. Upon the first step advance of the register brush L124, the off-normal contact set 500 operates to its alternate position whereupon the operating circuit of relay 4| I and magnet 40I are extended over the lower alternate contacts of relay II! to ground over the circuit traced and over the contacts of relay 3. Since the thousands digit dialed was one, a single impulse is transmitted in the impulse series and brush 424 is therefore advanced to the first terminal position of its arc. Upon the termination of this impulse series, relay 4| I releases.

In the meantime, however, the connection of ground to the trunk finder start conductor 420 has caused the operation of the group start relay I0 IL of Fig. 7, which is allocated to the first subgroup of ten trunks in the main group of one hundred trunks. Ten group relays are provided individual to the ten subgroups of trunks, the group relay of an intermediat group being shown at IfiII and the group relay of the first group being shown at IOIF. Group relay IOIL, upon operating, connects ground over its inner lower contacts to the level segment I03 of the vertical commutator T02 of all trunk finders having access to the group of trunks; connects ground over its lower contacts to the trouble alarm circuit and causes the operation of the start relay I09 of the first idle trunk finder, The trunk finders are divided into preferance subgroups in accordance with the subgroups of trunks whereby any trunk of a subgroup has the preferential use of trunk fiinders of a particular subgroup. If at any time all of the trunk finders which are the first choice preferance of a subgroup of trunks are busy, such subgroup of trunks then has second choice use of the trunk finders of another subgroup which are normally the first choice of another subgroup of trunks.

The trunk finder I00 is the first finder of the last subgroup of finders allocated as first choice to the last subgroup of trunks to which the group relay IGIL 'appertains. It will be assumed that this finder is idle and therefore upon the operation of relay IOIL, a circuit is established from ground over the back contact of relay I05, the upper contacts of relay 'IOIL, in-start conductor I96, over the middle normally closed contacts of the test and busy jack (0? of the trunk finder I09, over the inner upper-normal contacts of relay I08, through the winding of start relay I09 to battery and ground. Relay I09, upon operating, connects ground over its upper front contact to conductor II 0 and causes the operation of the stepping relay III in a circuit extending from ground over its lower contacts, interrupter contacts of vertical magnet H2, interrupter contacts of rotary magnet H3, lower winding of relay III to battery and ground over the inner lower back contact of relay I08. Relay H I, upon operating, causes the operation of the vertical stepping magnet 1I2 over a circuit extending from ground over the lower contacts of relay I09, over the contacts of relay II I, the upper back contact of relay H4, through the winding of magnet H2 and to battery over the inner lower back contact of relay I08. The brush shaft of the finder is thereby lifted one step placing the commutator brush H5 on the first vertical segment of the vertical commutator I02. The vertical olfnormal springs H6 are now operated to their alternate positions and the circuit of relay III is opened at the interrupter contacts of magnet I I2. Relay III now releases in turn releasing magnet H2 which in turn recloses the circuit of relay II I. Relay III reoperates and causes the reoperation of magnet H2. In this manner, magnet H2 is repeatedly operated and released to advance the brush shaft upwardly step-by-stepuntil the commutator brush H5 engages the grounded segment I03 whereupon a circuit is established from ground on such segment, over. brush H5 through the lower winding of relay H4, over the interrupter contacts of rotary magnet H3, through the lower winding of relay III to battery and ground over the inner lower back contact of relay I08. Relay III is thus held operated to prevent further stepping and relay H4, which is slow to operate, operates after an interval sufiicient to permit the switch brushes to cease vibrating following the completion of the last vertical stepping movement before they are started in their rotary stepping movement.

When relay H4 operates, it looks in a circuit from battery over the inner lower back contact of relay I08, through the winding of magnet H2, through the upper winding and over the inner upper front contact of relay H4 to ground over the lower contacts of relay I09; opens at its inner lower back contact the circuit extending over the lower contacts of off-normal springs H6, through the winding of release magnet HI; and transfers the stepping circuits control of stepping relay II I from the vertical magnet H2 to the rotary magnet H3. With stepping relay III now operated, the circuit of the rotary magnet II3 may be traced from ground over the lower contacts of relay I09, contacts of relay III, upper front contact of relay H0, through the winding of magnet H3 to battery and ground. Magnet H3 upon operating advances the brush sets of the finder one step in a rotary direction and opens at its interrupter contacts the holding circuit of relay III previously traced and the operating circuit thereof extending from ground over the lower contacts of relay I09, interrupter contacts of magnet H2, interrupter contacts of magnet 1 I3, and the lower winding of relay III to battery over the inner lower back contact of relay I08 whereupon relay III releases in turn releasing magnet H3. Magnet H3 upon releasing reestablishes the circuit of relay II I and relay III, upon reoperating, reestablishes the circuit of magnet H3 to advance the brush sets another step in the rotary direction. In this manner the brush sets are advanced step-by-step until the test brush H8 encounters the test terminal H9 of the calling trunk, I

It has been assumed that the calling trunk of Figs. 4 and 5 appears in the last terminal set of the level of the banks of the trunk finder corresponding to the commutator segment I03 which levels are partially shown and therefore when the brush sets have been stepped vertically to a position opposite such levels in their banks as illustrated and have been advanced ten steps in a rotary direction into engagement with the last terminalsets of such levels, a circuit will be established from battery applied through the winding of relay M9 or the trunk over conductor 42| to the test terminal 1H9, thence over test brush 1l8 through the lower winding of relay I20, upper back contact of relay'lllfl and through the upper winding of relay H I to ground on conductor H0. Relay III is held operated over this circuit to prevent further rotary stepping of the switch shaft and relay 120 operates sufficiently to close its inner upper contacts thereby establishing a circuit from battery through its upper winding over such contacts, the lower contacts of rotary magnet H3, contacts of relay HI to ground over the lower contacts of relay 109. Both of its windings being now energized, relay 120 fully operates to extend control conductors 425 to 43!, inclusive, of the trunk over brushes [2! to 121, inclusive, of the trunk finder and the upper'Nos. 3, 4 and 6 and lower Nos. 1 to 4 contacts of relay 12!} to conductors 128 to 134, inclusive, extending to the sender; to cause the operation of relay 108 in a circuit extending from ground over the oilnormal springs HB, the lower No. front contact of relay 120, through the lower winding of relay 108 to battery and ground; to connect sender conductor 135 over its upper No. 5 contacts and brush 136 to conductor M! which is multipled to corresponding bank terminals in the same vertical row of the upper finder bank; to open at its lower No. 5 back-contact another point in the circuit of release magnet Ill and to prepare a locking circuit for itself over its upper No. 1 front contact which will be effective following the operation of relay I08.

Relay 108, upon operating, extends trunk conductor 421 over terminal H9 and brush H8, the upper No. 2 contacts of relay 128 and the upper front contact of relay T08 to conductor H0 extending to the sender; completes the locking circuit of relay 120 extending from battery through the upper winding and upper No. 1 contacts of relay 120, over the middle upper contacts of relay 108 to ground on conductor 'Hll; transfers at its inner upper contacts the in-start conductor 'H'lli from the winding of start relay N39 to the outstart conductor lllzand through its upper winding to battery at the upper back contact of relay 731; at its inner lower back contact removes battery from the windings of relays HI and H4 and from the vertical magnet H2 and atits upper front contact shunts the upper winding of relay H L Relays H l and 1 is now release and relay 109, being slow'to release, releases after an interval sufiicient to allow ground to be applied to conductor 1 if! at the sender to hold relay 120 and relay M9 of the trunk operated.

When relay H4 releases the continuity of the outstart conductor T42 is established at its lower contacts whereby if a second trunk in the same subgroup should be in a calling condition, ground placed on the in-start conductor H16 will be effective to start the second trunk finder of the same subgroup of finders if it is idle over a circuit extending from conductor 1%, over the middle normal contacts of test jack m, the inner front contacts of relay M8, the lower normal contacts of relay H4, conductor 14-2, the lower normal contacts'of test jack 79?, the middle normal contacts of test jack 'lfll' associated with the second trunk finder of the same trunk finder lower No. 1 contacts to ground over inner lower group, thence over the upper normal contacts of relay 198' to the start relay of such second finder corresponding to relay 109. Had such second finder of the subgroup of finders been busy and consequently relay I08 had been operated, the start circuit thus traced would be extended over the front contacts of this relay, the lower normal contacts of test jack 101', the middle normal contacts of test jack 701", associated with the first finder of the next subgroup of finders, serving as second choice finders to the last subgroup of trunksand first choice to another subgroup of trunks, thence over the normal contacts of relay 108", of such finder to the start relay thereof. In a similar manner the instart conductors I06, 138, 139, etc., of the ten trunk subgroups may be extended to start trunk finders in the allocated first choice subgroups of finders or in other choice subgroups of finders.

When the trunk finder seized the terminals of the calling trunk and completed the circuit previously traced from battery through the'winding of relay M9, relay 419 operated and locked itself over its No. 1 upper front contacts directly to ground applied over conductor 42! from the trunk finder and at a later time from the sender. As soon relay 4|! releases following the completion or the registration of the impulse series in the digit register 400, a circuit is completed for transfer relay 413 which may be traced from battery through the winding of such relay, over the lower N0. 2 contacts of relay 4 l 9, over the lower No. 2 front contact of relay 415 and the upper back contact of relay 4|! to ground over the upper alternate contacts of off-normal contact set 590. Relay 4J3 thereupon operates and looks over its upper N0. 1 contacts, conductor Q32, the inner'upper back contact of charge relay Ell], conductor 433 to ground over the lower No. 1 contacts of relay M9 and to ground over the upper No. 1 contacts of relay M4 when relay 4M later operates. With relay M3 operated, the dialing circuit previously traced over the calling line loop and through the windings of relay 412 is disconnected from the windings of such relay and transferred to the connected sender. Relay M2 "now releases followed by the release of slow-toceived in the trunk, relays M3 and M9 will not have operated and therefore when relay M2 releases on the first impulse of this digit series, a circuit will be established from ground over the lower No. 1 back contact of relay M3, back contact of relay M2, the upper No. 1 contacts of relay M5, the lower alternate contacts of offnormal contact set 500, over the inner upper back contact of relay M1 to battery through the winding of relay H8. Relay M8 thereupon operates, locks over its upper No. 1 contacts to ground over the inner lower contacts of relay M6; establishes an operating circuit for the cut-through relay M4 extending from battery through the winding of such relay over the upper No. 2 con- I tacts of relay 4l8 to ground at the inner lower contacts of relay M6, which relay locks over its contacts of relay H6; prepares a path busy tone circuit over its lower No. 1 contacts; removes starting ground at its lower No. 3 back contact from the trunk finder start conductor 42C! and 

